1. Field of the Invention
This invention relates to door constructions in a motor vehicle, and more particularly to a construction of a door in a motor vehicle wherein reinforcing flanges are provided for increasing the rigidity of a triangular portion of a door not having a so-called triangular window.
2. Description of the Prior Art
A so-called triangular window in a door of a motor vehicle is openably provided at the forward end of the door where belt lines of a main body of the door and the window frame intersect each other at an acute angle. However, most of the motor vehicles produced and used at present lack triangular windows.
In a door not having a triangular window, the resistance of the window frame portion of the door to bending is reduced at the location where the triangular window would otherwise be provided, and the window glass and frame are drawn outwardly under the influence of the air stream and wind pressure during high speed driving of a vehicle so as to create gaps between the window frame portion of the door and the vehicle body, whereby noise in the passenger compartment is increased and air tightness of the compartment is deteriorated.
To overcome this problem, heretofore an arrangement has been adopted as shown in FIG. 1, such that at a location below a triangular portion 4 located at the forward or rear end of a door 1, where belt lines 2 of a main body of door 1 and a window frame 3 of the door intersect each other at an acute angle, flanges 7 are projected from top portions of a door outer panel 5 and a door inner panel 6 inwardly and outwardly in the thickness-wise direction of the door, respectively, and these flanges 7 are welded to each other, whereby the resistance to bending of a lower part of the triangular portion 4 is increased.
Two pairs of the aforesaid flanges 7, each being of a substantially square shape, are normally arranged in the longitudinal direction of the door, with each pair of flanges projecting from the door inner panel 6 and the door outer panel 5, respectively, and each opposing pair of flanges are respectively spot-welded each at one point, i.e., at a total of two points in the longitudinal direction of the door.
However, in the conventional reinforcing construction as described above, the projecting forms of the flanges 7 are complicated, difficulties are encountered in the work of surface-of-surface alignment of these flanges 7 due to the presence of the plurality of flanges, differences in height tend to occur between the flanges 7, workability during welding is low, errors in assembly tend to occur, and hence, the above-described reinforcing construction is disadvantageous in that distortions due to the welding tend to be caused to the door inner panel 6 or the door outer panel 5.
Moreover, because of the form of the joint between the flanges 7 as shown in FIG. 1, if a bending force is applied to the door window frame 3, then a torsion acts on a mounting portion of the door window frame 3, and this torsion causes the door inner panel 6 and the door outer panel 5 to move relative to each other, whereby the flanges 7 tend to be twisted.